<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="../react18/react.development.js"></script>
    <script src="../react18/react-dom.development.js"></script>
    <script src="../react18/babel.min.js"></script>
    <script src="../react18/prop-types.js"></script>

</head>

<body>
    <div id="app"></div>
    <script type="text/babel">
        /*创建refs
        refs使用 React.createRef()创建  创建后通过ref属性添加到元素上
        在构造组件时，会把当前书写ref属性的DOM交给创建的iptEle保管,
        并放在它的current属性上
        创建一个Refs只能存放一个DOM
        */
        class Parent extends React.Component {
         iptEle = React.createRef()

         render(){
            return(
                <div>
                <input type="text" ref={this.iptEle}/>   
                <button onClick={this.handle}>输入</button> 
                </div>
            )
         }
         handle=()=>{
            console.log(this);
            const {value}=this.iptEle.current
            alert(value)
         }
        }

        const root =ReactDOM.createRoot(document.getElementById("app"))
        root.render(<Parent/>)
    </script>
</body>

</html>